Users perform many operations on an information processing device such as a mobile telephone and portable game device using a touch panel, in addition to operation keys attached to the main body. In particular, many recent information processing devices have a high-definition display screen, and such an information processing device makes intuitive operations possible by combining icons and touch panel operations. An example of an information processing device having such a user interface is shown in FIG. 2. An operation is performed on the information processing device shown in FIG. 2 by using a touch panel and operation keys provided thereunder.
Patent Literature 1 discloses a technology in which a user performs an operation using two fingers on a touch panel to select icons.
[PTL 1]
    Japanese Patent Kokai Publication No. JP2001-356878A